Yes this is true. I built the Statue of Zeus in a city that already had a barracks and was reimbursed 620 hammers, which is twice the production cost.Also I think the building's reimbursement scale with game speed, in addition to its base cost scaling with game speed.
Meaning a building that cost 200 in standard (and being reimbursed 200) cost 300 in epic,and is being reimbursed 450.
Anyone else noticing something like that ?
Thank you for your suggestion.
Thank you very much for your help. May the ancient ruins be with you!